A rotary actuator, or for that matter, a linear actuator, as well, can be controlled by a servo valve and a servo valve amplifier to move to a particular position in a given system. The ultimate static position of the shaft is maintained in a specific location provided the load that is on the shaft of the actuator is within the design of the system. This would apply to both a rotary and a linear type actuator. An external feedback system, such as a potentiometer, would feed back position information to an amplifier which would compare the output of a position reference to the position information coming from the feedback potentiometer. When the two voltages or currents are equal, the system would null out and the position of the actuator would be established. This system would hold that particular static position regardless of the nature of the load unless the load exceeded the hydraulic forces in the actuator. Another type of system would involve a manual movement of a control by an operator to control the amplifier which is feeding the servo valve. A typical type device, sometimes known as a joy stick, is used to move the actuator from one position to another position. Once the system has stopped, the actuator would maintain its particular position because of an external feedback system that would feed back the position information into a controller or amplifier and maintain that particular position regardless of the load provided that the load is in the load design range of the given actuator. Both of these systems described above are old in the art and have been used for many many years in controlling rotary and linear actuators.
My invention improves upon the state-of-art and allows an actuator shaft to be accurately controlled so that the specific position of the shaft can be established at any two pre-selected points in a given system and be able to return to those points accurately. This would be functional for both rotational and linear type actuators. Also, the velocity of the speed of rotation to each position is also adjustable by my invention. The system can be expanded so that more than two positions or velocities can be obtained. That is, the actuator could stop at any number of positions depending upon the number of reference potentiometers that are designed into the system. This is also true for the velocity. The deceleration can be fixed or made adjustable depending on the design and requirements of a system.